Commutator brush with lifting member



Aug. 23, 1932. A Q HENRY 1372,948

COMMUTATOR BRUSH WITH LIFTING MEMBER 4 Filed April 28, 1931 ATTORNEY Patented Aug. 23, 1932 P UNITED S TE PATENT OFFICE ALBERT G. HENRY, OFIRONTON, OHIO, ASSIGNOR TO HENRITE PRODUCTS CORPORA- TION, INQ, IRONTON, OHIO, A CORPORATION OF OHIO GOMMUTATOR BRUSH WITH LIFTING MEMBEB Application filed April 28, 1931. Serial No. 533,433.

This invention relates, generally, to commutator brushes for dynamos; and the im vention has reference, more particularly, to a novel commutatorbrush provided with a lifting member especially adapting the same for use on repulsion-induction motors.

Repulsion-induction motors of the lifting brush type have their brushes in contact with the rotor commutator when the motor starts up from rest, so that the motor at this time operates as a straight repulsion motor. When the motor reaches a desired speed, a centrifugal device operates to move the brush frame away from the commutator sothat the brushes are lifted off of the commutator, and at the same time a suitable device serves to short-circuit the commutator bars so that thereafter the rotor operates as a squirrelcage rotor. These motors thus possess the high starting torque of a repulsion motor and the subsequent constant speed of an induction motor. Considerable difiiculty has been involved heretofore in insuring the proper lifting of the brushes from the commutator when the motor rotor reaches'the desired speed after starting. Heretofore, these lifting brushes ofttimes fail to leave the commutator when the motor-reaches the desired operating speed resulting in the wasting of current, burning of the commutator and shortening the. life of the brushes, together with the production" of excessive noise. The principal object of the present'inven- 35 tion lies in the provision of a novel commutator brush having a lifting .member which is so constructed and arranged as to positively cause the brush to leaveor disengage the commutator when the motor rotor has attained the desired speed after startmg. I Another object of the present inventionis to provide a novel commutator brush having'a lifting member or wire molded or otherwise permanently secured therein, which lifting member by engaging the brush frame when this frame moves away from the commutator in use, positivelyinsures the removal orlifting of the brush from the commutator.

Still another object of the present inven tion lies in the provision of a novel commutator brush with lifting memberwhich is of simple, strong construction and has a long life in use. v

Other objects of this invention, not atthis 5 time more particularly enumerated, will be clearly understood from the followingdetaileddescription of the same.

The invention is clearly illustrated in the accompanying drawing, in which:

Fig. 1 isa view in rearelevation of a. repulsion-induction motor equipped with the novel commutator brushes with lifting members of the present invention, the motor end cover being removed.

Fig. 2 is an enlarged fragmentary view taken substantially along line 2-2 of Fig. 1. Fig. "3 is aperspective view of. a pair of the novel lifting brushes of the present in vention, the same being interconnected by a 7 flexible, electric conductor; and p Fig. 4 is 'a plan view of a pair 'ofthe brushes with parts'broken away to showthe manner of inserting the lifting member or wire and the flexible, electric conductor into n the brush body. 'Similarcharacters of reference are employed in all of the above described views to indicate corresponding parts. 1

Referring nowto, said drawing, the reference numeral l'designates a motor-of the repulsion-induction type having stator windings 2 and a rotor 3 which is provided with a commutator 4 at the rear end thereof. Alternating current is supplied to the statorwindings 2 by means of cable 5. Rotor or armature 3 has a shaft 6 which is rotatably mounted in suitable bearings provided in the motor end-covers, the rear end-cover 7 alone being illustrated in the drawing, 00 which end cover has a bearing housing 8 for receiving the shaft 6. I f

A commutator brush frame 9 has ahollow hub portion 10 which surrounds the shaft 6 in spaced relation therefrom. Hub portion 96 10 is providedwith an inwardly directed annular flange member 12 at its. forward end portion, which flange projects into an annular groove 13 provided in a ring-shaped yoke member .14. A coil compression spring '16 m surrounds the shaft 6 and bears at one end against a collar 17 fixed on this shaft and at its other end against an inwardly directed annular flange 19 formed on the ring-shaped yoke member 14:. Spring 16 by pressing forwardly upon yoke member 14 causes this yoke member to urge commutator brush frame 9' forwardly, thereby tending to move the lifting brushes 18 carried by this brush frame, into engagement with the commutator. Thus, when the motor is at rest, spring 16 acting through yoke member 14, flange 12 and hub portion 10 of the brush frame, acts to urge this brush frame forwardly so that brushes 18 engage against commutator 4.

Tortion springs 20 are mounted on radial posts 21 extending outwardly from the brush frame 9 and the end portions 22 of these torsion springs bear against the ends of lifting brushes 18, so that these brushes are held firmly in engagement with the commutator 4 when the brush frame 9 is held adjacent the commutator under the action of spring 16. The yoke member let carries an annular and somewhat flexible electrical conducting member 24: which is adapted to engage inward projections 25 formed on the commutator bars of commutator 4 to thereby short-circuitthese bars when the motor is running at normal speed.

A. pair of spaced rods 15 extend parallel to shaft 6 from the forward portion of the motor rotor 3 to the rearward portion thereof where they are connected to the conducting member 24. A suitable centrifugal device such as centrifugal governor (not shown but well known to those skilled in the art) is positioned at the forward end of rotor 3 and is adapted to actuate or move rods 15 rearwardly when the motor attains a. predetermined speed. Thus. when the motor picks up the desired speed after starting, the rods 15 are pushed rearwardly by the centrifugal device, thereby moving yoke member 14 rearwardly and causing brush frame 9 to be moved rearwardly so that brushes 18 disengage the commutator 4. Just after the brushes 18 disengage this commutator the electric conductor member 24 engages the inward projections 25 of the commutator 4,

thereby short-circuiting this commutator and causing the rotor to thereafter operate as a squirrel-cage rotor. The repulsion-induct-ion motor structure heretofore described is well known to those skilledin the art and forms no part of the present invention and is therefore thought to require no further description.

The novel liftingbrushes 18 constitute the improvement of the present invention and tion product, as, for example, bakelite. At the time of fabricating the brush 18, the same is provided with a lifting member or wire 26 of angular shape. Lifting member 26 has a shank portion 27 that extends into the interior of the body of the brush 18 and an extetior head portion that extends at right angles to the shank portion 27. Shank portion 27 is preferably molded into the body of the brush at the time of molding the brush.

Brushes 18 are connected in pairs by flexible electrical conductors 28 which have their end portions preferably molded in the brush bodies. To facilitate the easy molding of each lifting member or wire 26 along with the end portion of the flexible electric conductor 28 into the brush body, the shank portion 27 of the lifting member or wire 26 is preferably soldered as indicated. at 32 to the end portion of the flexible conductor 28. In forming the brushes 18, the shank 27 of lifting wire 26 is first soldered to the end portion of the flexible conductor 28 and these two members are then inserted into the mold adaptedto receive the composition or mixture making up the brush 18. This mixture is then inserted and preferably molded under heat and pressure to form the brush of the invention. By this molding process the lifting member or wire 26, together with the end portion of the flexible electric conductor 28 is firmly and permanently embedded in the brush body.

The head portion of the lifting member 26 being bent at right angles to the shank 27 thereof. engages the brush frame 9 when this brush frame is moved away from the commutatorby the action of rods 15 in use. This is especially illustrated in Figs. 1 and 2, wherein the lifting member 26 is shown engagingin a'depression 30 formed in the brush frame 9. Thus, as this brush frame moves away from the commutator 4, the head portions of the lifting members 26 engage the frame 9, thereby positively moving the brushes 18 away from the commutator and preventing contact of these brushes with the ammutator after the motor has attained its desired speed.

It will be apparent that the lifting members 26 and the conductors 28 may be cemented into the brushes 18 or otherwise secured to the same, if desired, but molding these members directly into the brush body is found to be most satisfactory in practice. Also, it will be apparent that'these members need not be soldered together before molding in some instances.

As many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made Without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawing shall 3 be interpreted as illustrative and not in 'a limiting sense.

What is claimed is 1. A lifting commutator brush comprising, a molded brush body and an angular lifting member, said lifting member having a shank portion molded in said brush body and a head portion extending exteriorly of said brush body and at right angles to said shank portion for engaging a brush supporting frame to thereby effect the positive lifting of the brush in use.

2. A pair of lifting commutator brushes for use on repulsion-induction motors comprising, a pair of brush bodies having liftng wires fixedly embedded therein, a flexible conductor joining said brush bodies and having its end portions embedded in said brush bodies adjoining said lifting wires, said lifting wires having exterior head ortions for engaging a brush frame to there y effect the positive lifting of the brushes in use. 3. A lifting commutator brush compris- 111g, duotor having an end portion molded in said brush body, and an angular lifting Wire, said lifting wire having a shank portion soldered to said conductor end portion and molded in said brush body and a head portion extending exteriorly of said brush body and at right angles to said'shank portion for en- "aging a brush supporting frame to thereby effect the positive ifting of the brush in use. In testimony, that I claim the invention set forth above I have hereunto set my hand this 8th day of April 1931.

ALBERT o. HENRY,

a molded brush body, a terminal con- 

